Events are triggered by the Elgg framework when a certain thing happens - for example when a blog post is created or when a pingback is received.

By listening to events your plugin can opt to have code executed when that event occurs.

Registering an Event handler

To register a hook, use the function 'register_elgg_event_handler', eg.

register_elgg_event_handler('init','system','entities_init');

Parameters

• $event The event type.
• $object_type The object type (eg "user", "object" etc) or 'all'.
• $function The name of a valid function to be run.
• $priority The priority - 0 is first, 1000 last, default is 500.

register_elgg_event_handler('init','system','entities_init');

Your Event handler

Your event handler should have the following prototype:

function event_handler_function($event, $object_type, $object)
{
 
    ... do stuff ...
 
}

This function MUST return true or false depending on success. A false will halt the event in its tracks and no more functions will be called.

Parameters

• $event The event type.
• $object_type The name of the type of entity (eg "user", "object" etc) or 'all'.
• $object The object

Special events

Elgg has three special events that occur on (virtually) every pageload.

Boot

System boot connects to the database, starts the session, and establishes some base variables and configuration settings. This event is inaccessible to plugins, as it is triggered before plugins are loaded.

Init

This event is intended for plugins to perform configuration procedures. It is recommended that you add submenu items and perform similar activities in a yourplugin_init function attached to this event.

Pagesetup

Sometimes it's necessary to perform further procedures after the full Elgg framework has been loaded, but before anything has been drawn to the page. This event is called during the first reference to elgg_view (whether directly or through a helper function like elgg_view_title or list_entities).

event handler, events, event system

Last updated 531 days ago by Pete Harris